1. Field of the Invention
The present invention relates to an ink jet recording method and an ink jet recording apparatus.
2. Related Background Art
Because ink jet recording apparatuses which can perform recording on recording media such as paper, cloth, plastics and sheets for OHP enable a high-density and high-speed recording operation, they have been widely used and commercialized as information processing systems, for example, printers as output means for copiers, facsimile machines, teletypewriters, word processors and workstations, or handy or portable printers for personal computers, host computers, optical disk equipment, and video/visual equipment.
In general, such an ink jet recording apparatus mainly comprises a carriage on which a recording head unit consisting of a recording head and an ink tank is mounted, a means that transports a recording medium, and a control means for controlling them. In this configuration, recording can be performed on the recording medium by serially scanning the recording head in the direction (hereinafter referred to as main scanning direction) vertically intersecting the transport direction (hereinafter referred to as sub scanning direction) of the recording medium and discharging ink drops from a plurality of discharge outlets of the recording head during this scan. Then, when this one-line recording is terminated, the recording medium is intermittently transported only by a predetermined amount. Further, an ink jet recording apparatus having a recording head, in which a plurality of discharge outlets which discharge ink drops are aligned in the sub scanning direction, has also been developed, and this ink jet recording apparatus can perform recording of a width (normally, a width of the head) that corresponds to the number of discharge outlets in one scan.
Because the ink jet recording apparatus described above performs recording by discharging ink drops, its running cost is cheap and its operation is also quiet. Because the ink jet recording apparatus can perform recording for the width of the head in one scan, it also enables a high-speed recording operation and has been widely used.
Further, a color ink jet recording apparatus equipped with 3- or 4-color recording heads, in which discharge outlets are aligned in the sub scanning direction, is also put to practical use. This ink jet recording apparatus installs four types of recording heads and ink tanks which correspond to three primary colors of yellow (Y), magenta (M) and cyan (C) or the four colors including black (B) in addition to these three primary colors, and can form a full-color image by the conventional ink jet recording method. Furthermore, in recent years, an ink jet recording apparatus, in which recording heads, which also discharge a lower density ink than each ink in addition to Y, M and C, inks are also installed and which enable representation of a smoother graduation, has also been developed.
Thus, an ink jet recording apparatus in which the single unit is used to enable formation of both a full-color image and only a black image such as a character is becoming the mainstream.
Hereupon, when a color image is formed on plain paper by the ink jet recording method, because the prevention of an ink blot in the boundary region of each color of black, yellow, magenta, and cyan and the prevention of the high density and feathering of a black image are conflicting issues, it is very difficult to obtain a high-density image having no ink blot and feathering.
This is because ink is prevented from blotting in the boundary region of each color by using quick-drying ink of which permeation rate into a plain paper is fast when a color image is recorded on the plain paper by the ink jet recording method. However, when the quick-drying ink is used, a black image is low in its density and a colored image part other than the black image has low color development. Moreover, because the quick-drying ink is easy to permeate along a paper fiber, feathering is easy to generate. In particular, characters printed in black are conspicuous in feathering and become unclear characters short of sharpness as compared with those printed in other colors. As a result, the quality of an image deteriorates greatly on the whole.
Accordingly, to obtain a high quality image with density of a black image part that is high and which causes no feathering, a method is sometimes used in which much ink, the permeation of which into plain paper is comparatively slow, is applied to the same location. However, because this method is slow in the permeation of each ink into paper, it conversely generates a blot. In particular, in the boundary area between a black image part and a color image part, a blot in black ink and color ink is generated and the quality of an image deteriorates greatly.
To improve these defects, an ink jet recording method of installing a heater in a recording apparatus, accelerating the drying of ink, and obtaining a blot-free color image having high color development between colors is also put to practical use. However, because this method installs a heater capable of drying ink in the recording apparatus, the unit becomes larger and more expensive.
Then, as described in Japanese Patent Application Laid-open No. 3-146355, a method of performing no printing in the area along the boundary area between the black image part and color image part is proposed. However, this method has a defect that data to be printed may change when an image is formed.
Further, as described in the Japanese Patent Application Laid-open No. 4-158049, a method of performing recording by installing a plurality of color heads for color recording and a head for character recording and switching the plurality of color heads and the head for character recording based on recorded data is proposed. Because in this method the black ink of the head for color recording and the black ink of the head for character recording differ, if a black image recorded by the head for color recording and a black image recorded by the head for character recording coexist, a sense of incompatibility caused by the quality difference of both images is generated.
Furthermore, a method of preventing a blot in the boundary region between a black image part and a color image part is taken into consideration by overlappingly applying three-color ink of Y, M and C to form a black image without performing printing with black ink in a fixed black area along the boundary between the black image part and color image part. However, the black image formed by overlappingly applying the three-color ink of Y, M and C has worse color development than the black image formed with only normal black ink.
On the other hand, as described in the Japanese Patent Application Laid-open No. 56-84992 and the Japanese Patent Application Laid-open No. 64-63185, a method of preventing a blot and feathering using a fluid which insolubilizes dyes is also proposed. In other words, because the fluid that insolubilizes the dyes and ink are mixed and fused on a recording medium, the ink is not permeated into the recording medium and the blot and feathering can be prevented.
The ink jet recording method described in Japanese Patent Application Laid-open No. 56-84992 is used to coat recording paper with a material for previously fixing the dyes. However, when printing is performed by this method, specific recording paper must be used, and to coat it with the material for previously fixing the dyes, the unit becomes larger and more expensive. Further, it is difficult to evenly coat the recording paper with the aforementioned material at a predetermined film thickness.
Moreover, as described in the Japanese Patent Application Laid-open No. 64-63185, there is also a method of making the colorless ink that insolubilizes the dyes adhere on a recording medium by an ink jet recording head.
Because this method makes the dot diameter of aforementioned colorless ink larger than the dot diameter of the ink for an image, desired characteristics can be satisfied even if the impact position between the image ink and the colorless ink is shifted. However, because the amount of colorless ink printed on the part that corresponds to the image position normally becomes larger than the amount of the image ink applied, there are such problems to be solved that the drying time of the ink is not only prolonged but an image becomes exceedingly unclear.
Further, in Japanese Patent Application Laid open No. 7-195823, by applying the previously described colorless ink to the surface of a recording medium prior to the ink jet recording, the color print can be obtained in one pass.
The methods disclosed in each of the aforementioned publications all have problems to be solved. Because the colorless ink described previously insolubilizes the dyes in ink, the ink blot may be prevented from forming between respective colors when this method is applied to color recording.
The applicant of this patent has solved the aforementioned problems, and proposes an ink jet recording method whereby a fluid which insolubilizes dyes is used. The amount of consumption of this fluid is suppressed to the utmost, and as a result a low running cost is realized, more excellent water resistance (or imperviousness to water) than before is shown even on plain paper, a high density image can be obtained, and an image of high color development with no blot between colors is produced when the method is applied to color recording (Japanese Patent Application Laid-open No. 8-39795).
Furthermore, to obtain high density images, a method of performing recording on a recording medium at three stages is used. These stages comprise a first stage where ink is discharged to a predetermined area, a second stage where the fluid which insolubilizes the dyes in the ink is discharged to the predetermined area, and a third stage where the ink having the same color as in the first stage is discharged to the predetermined area. Accordingly, an image with high density and clear contrast can be obtained by applying a greater amount of ink on the whole as compared with the image by the conventional method.
However, when the conventional ink jet recording method described above is used, the following problem arises.
In other words, because the ink applied onto the recording medium at the first stage and the treatment fluid applied at the second stage react, the ink is non-liquefied, and the ink is applied at the third stage, the time required for permeation and the time required for fixing become prolonged. This problem interrupts a high-speed recording operation.
If the image density satisfies a fixed level, even a light density among the densities is not inferior on visual inspection so long as it exceeds the predetermined level.
Moreover, in recent years, to obtain a higher quality image, high resolution has been obtained by forming recording fluid drops as small fluid drops. However, in order to achieve such high resolution, the recording data size to be processed reaches a great amount, the data processing time in a host computer and the transfer time of the data transferred from the host computer to a recording apparatus are prolonged, and the throughput of the entire system is greatly reduced.
To solve this problem, a method of performing recording using a matrix pattern is taken into consideration. This method transfers the data processed at comparatively low resolution and high-value quantized by a host computer to a printer main body and performs recording by developing received data into a predetermined matrix using the printer main body. For example, recording is performed by quantizing (3 bits) data into quinary values at a resolution of 300 by 300 dpi using the host computer and by developing to a binary value of 600 by 600 dpi (a matrix of 2 by 2) using the printer main body, whereby the host computer processing becomes 300 dpi and accordingly its load is reduced. Also, because the data transfer is 300 by 300 dpi, 3 bits, an advantage of thinning the data amount to about 75% is obtained as compared with the 600 by 600 dpi, binary data. Such method of using the matrix pattern is effective for an image such as a photograph wherein emphasis is laid on graduation rather than sharpness.
Hereupon, in the ink jet recording method, when an image is recorded on a recorded material called the so-called plain paper, the water resistance of the image is insufficient, and for the recording of a color image, a high-density image causing no feathering and an image causing no blot between colors cannot coexist, and the color image with good image fastness properties and good quality is not obtained.
In recent years, as a method of improving the water resistance of an image, an ink having a water resistance in the color material contained therein has also been put to practical use. However, because the ink is still insufficiently water resistant, and is difficult to dissolve in water after drying, the nozzle clogging of a recording head, that is, the clogging of an ink discharge outlet, is likely to occur. To prevent this, the configuration of the apparatus becomes complicated.
Further, many technological developments for improving the fastness properties of a recorded material have been proposed. For example, in Japanese Patent Application Laid-open No. 58-128862, an ink jet recording method of previously recognizing the position of an image to be recorded on the recorded material and performing recording by overlapping recording ink and treatment ink has been devised. In that method, an image is drawn by the treatment ink prior to the recording ink, the treatment ink is overlapped on the image of the recording ink drawn previously, and after overlapping of the recording ink on the image of the treatment ink drawn previously, the treatment ink is further overlapped. Further, in Japanese Patent Application Laid-open No. 8-52867, a method of discharging the treatment fluid to each pixel at a predetermined ratio is disclosed. Further, in Japanese Patent Application Laid-open No. 9-226154, special attention is paid to the edge part of an image to be printed, and there is disclosed a configuration that the treatment fluid is discharged to the image other than the edge part at a predetermined ratio while the treatment fluid is always discharged to the edge part of the image, whereby the treatment fluid is prevented from being consumed more than necessary and the water resistance is made more accurate.
As disclosed in Japanese Patent Application Laid-open No. 9-226154, to apply an effective treatment fluid, the edge part of an image to be printed is selected, and the treatment liquid is applied to the image of the edge part and the image other than the edge part at respective predetermined ratios. However, for this invention a very complicated and large-scale circuit configuration is needed as an electrical hardware means, which results in an increased cost. Also, to perform such processing on a software basis, a non-realistic enormous amount of time would be required for a high-resolution recording apparatus.
Further, to apply an effective treatment fluid to a boundary, the edge part of an image to be printed is selected and the treatment fluid is applied to the image of the edge part and the image other than the edge part at respective predetermined ratios, so that a very complicated and large-scale circuit configuration is needed as an electrical hardware means, which results in an increased cost. Then, to perform the aforementioned processing on a software basis, an unrealistic enormous amount of time would be required for a high-resolution recording apparatus.
A first object of the present invention is to provide ink jet recording method/apparatus for solving the conventional technical issues described above, preventing the fixing time of ink from being prolonged without considerably decreasing the density of an image, and enabling a high-speed recording operation.
To attain the first object described previously, an ink jet recording method of the present invention is provided in an ink jet recording apparatus which comprises a first head having a discharge outlet which discharges a first ink showing a first color, a second head having a discharge outlet which discharges a second ink showing the same color as the first color, and a third head having a discharge outlet which discharges a treatment fluid that insolubilizes the first ink and the second ink, wherein when an image is formed by discharging the ink or treatment fluid to an area where recording is performed according to the same image data, in the order of the first head, the third head, and the second head, based on the same image data, and regardless of said same image data, the application amount X1 of the first head for the area and the application amount X2 of the second head for the second head are set to X1 less than X2 or X1 greater than X2.
To attain the first object described previously, an ink jet recording apparatus of the present invention comprises a first head having a discharge outlet which discharges a first ink showing a first color, a second head having a discharge outlet which discharges a second ink showing the same color as the first color, and a third head having a discharge outlet which discharges a treatment fluid that insolubilizes the first ink and the second ink, wherein when an image is formed by discharging the ink or treatment fluid to an area where recording is performed according to the same, in the order of the first head, the third head, and the second head, based on the same image data, and the application amount X1 of the first head for the area and the application amount X2 of the second head for the second head are set to X1 less than X2 or X1 greater than X2.
The configuration described above decreases the entire amount of application to a recording medium, and as a result, can reduce the fixing time.
Further, a second object of the present invention is to provide an ink jet recording apparatus and an ink jet recording method which generates the treatment fluid quantized data from n-valued ink quantized data and performs recording using the so-called matrix pattern method based on these data, whereby an electrical hardware cost is suppressed, the increase of the software processing time is prevented, sufficient water resistance is obtained by applying a sufficient amount of treatment fluid, the increase of the running cost due to the increase of the amount of treatment fluid used can be prevented by avoiding the application of treatment fluid more than is necessary.
To attain the second object, an ink jet recording apparatus of the present invention, in addition to the aforementioned ink jet recording apparatus, further comprises a means which generates the treatment fluid quantized data based on the ink quantized data n-valued at predetermined resolution, a means which allocates the ink data and treatment fluid data using a matrix consisting of a plurality of pixels, based on the ink quantized data and the treatment fluid quantized data, a first control means which controls the discharge of the ink by the ink head unit for a pixel subject to the allocation, based on the ink data allocated by the allocating means, and a second control means which controls the discharge of treatment fluid by the treatment fluid head unit for a pixel subject to the allocation, based on the treatment fluid data allocated by the allocating means.
Further, to attain the second object, the ink jet recording method, in addition to aforementioned ink jet recording method, further comprises the steps of generating treatment quantized data based on the ink quantized data n-valued at predetermined resolution, allocating the ink data and the treatment fluid data using a matrix consisting of a plurality of pixels according to the ink quantized data and treatment fluid quantized data, controlling the discharge of ink by the ink head unit for the pixel subjected to the allocation, based on the allocated ink data, and controlling the discharge of the treatment fluid by the treatment fluid head unit for the pixel subject to the allocation, based on the allocated fluid data.
Furthermore, a third object of the present invention is to-prevent the increase of the running cost due to the increase in the amount of treatment fluid used by generating the treatment fluid data from the ink data binarized based on a pattern predetermined per density and is to apply an amount of treatment fluid enough to obtain the effect of treatment fluid by generating the treatment fluid data based on the pattern of the binary ink data that can be estimated per density.
The ink jet recording apparatus of the present invention, so as to attain the third object, performs recording by relatively scanning, across a recorded material, a record head equipped with an ink discharge unit and a treatment fluid discharge unit which discharges the treatment fluid acting on the ink by making contact with the ink, and comprises ink data generating means which generates binary data for the ink using a predetermined pattern regarding a predetermined area, treatment fluid data generating means for generating treatment fluid data based on the ink data, and a recording control means which controls discharge of the ink and the treatment fluid to the pixel to be applied, based on the ink data binarized by the ink data generating means and the treatment fluid data generated in the treatment fluid data generating means. The treatment fluid data generating means generates the treatment fluid data for applying the treatment fluid to the same place where the ink is applied, based on the binary ink data when the density in the predetermined area is below a predetermined density, and generates the treatment fluid data so that a thinned amount of the treatment fluid may be applied to the place where the ink is applied, based on the binary ink data when the density of the predetermined area is larger than a predetermined density value.
Additionally, according to the present invention, a treatment fluid acts on ink by making contact with the ink, for example, and contains a component having the action by which color agents in the ink are insolubilized or cohered. Such fluid can show an effect of improving printability, such as improvement in the water resistance of a recorded image, increase of density, prevention of a blot, and reduction of feathering.